Need help calculating final dilution factor for double dilution

Question

So I am trying to calculate a dilution factor of an already diluted stock suspension. So my initial solution has 100ul of cell suspension, 400ul of PBS and 250ul of dye. My calculated DF for this is 7.5. My final solution is 100ul from original solution + 100ul of PBS. All I want to know is what is the final DF for my stock cell suspension. I know it is probably easy but I just can't figure it out. Thanks for any help

Answer 1

You question is not very clear.  If you take 100 ul of original and add 100 ul PBS that is a 1:1 or 2 fold dilution.  If you have 100 ul of cell suspension + 400 ul PBS + 250 ul dye, that is a 7.5 fold dilution.  If you are talking about combining these, the is it a 15 fold dilution or a DF (as you call it) of 15.  Again, I'm not sure I completely understand your situation.